It has been the practice in the insulation of heating and air conditioning ductwork to seal the corners of the ducts, whether straight or curved. Typically, ninety degree angle edging made of either sheet metal, plastic or even paper has been used. The insulation industry has traditionally used tin (plated) edges 2".times.2" on corners of ductwork, scroll fans and other essentially square edges. These tin plated edges are held in place with tape or contact adhesive which can be brush applied. Thereafter canvas, plastic, or other suitable decorative fabric is stretched around the structure and glued in place. In the case of canvas, further coatings are painted on to shrink the canvas to a tight fit and seal it to provide an attractive finish. Tin edges or galvanized sheet metal are generally made of approximately twenty-four gauge (0.023") thick material.
Murasho Co. Ltd. offers an edging material that is formed in a metal roll consisting of a flat surface with overlapping discrete segments depending from the flat surface at a ninety degree angle. The discrete segments facilitate application of the flat surface on contoured edges. The Murasho product is identified as Roll Kiku-za or squeezed sheet. Similarly, Zeston (Manville Corporation) has marketed a metal end capping product that is essentially the same. A need has arisen for an inexpensive, easy to apply corner edge, starting at 11/2".times.11/2" and going up to 3".times.3" to accommodate the normal insulation thicknesses used on ductwork and similar structures that are generally 1" to 2" thick (or more).